Hydraulic Hybrids and Holistic Design: A New Approach to Delivery

12th October 2012 by Mike Heskitt

It’s good to see another example of the transportation industry adopting the RIGHT hybrid powertrain for a specific need and vehicle type. A recent article in Fleet Owner reports that UPS has purchased 40 hydraulic hybrid delivery vans partially funded through the U.S. Dept. of Energy’s Clean Cities program.

For heavy vehicles with more stop-and-go driving than steady-state drive cycles, we’ve seen that hydraulic hybrids have a clear advantage over electric hybrids in relation to power recovery efficiency and lifecycle cost.

It is interesting to note that, in most cases where hybrid drivelines are introduced, manufacturers simply swap out the traditional driveline and integrate the hybrid. This process may also include engine downsizing for additional fuel-economy gains. Recognizing the vehicle weight and drive cycle plays a large part in the resulting fuel economy, we have to wonder how much more than the 35 percent improvement in fuel economy that the article references might be gained with an optimized design that reduces weight and improves system efficiencies.

Although certainly a more extreme drive cycle and higher weight, the 110 percent improvement achieved by the BUSolutions hydraulic hybrid design is far above the results obtained in any “swap out” integrations we’ve seen in the bus industry, and it is a good case in point to argue that far more gains can be made with a holistic design approach using optimization than with a simple powertrain choice alone can provide.


Altair’s BUSolutions project features a series hybrid hydraulic powertrain, one of many innovations that gave it twice the fuel economy of other buses